Rimfire type firearms having centerfire firearm components and related methods

ABSTRACT

Firearms include some components originally configured for use with centerfire cartridge ammunition, such as a lower portion, and other components configured for use with rimfire cartridges, such as an upper portion and magazine. The firearm is thus configured for firing rimfire cartridge ammunition, although some components of the firearm may be characterized as centerfire firearm components. Methods of fabricating firearms involve assembly of a rimfire upper portion with a centerfire lower portion. A magazine is provided that is configured to couple to the centerfire lower portion, and to feed rimfire cartridges from within the magazine into the rimfire upper portion. Methods of adapting a centerfire firearm for use with rimfire cartridges involve removal of a centerfire barrel and upper portion from a centerfire lower portion, and attachment of a second upper portion and a second barrel, each configured for use with rimfire cartridge ammunition, to the centerfire lower portion.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims the benefit of the filing date of U.S. Provisional Application Ser. No. 61/752,297, filed on Jan. 14, 2013, the entire disclosure of which is incorporated herein in its entirety by this reference.

TECHNICAL FIELD

The present disclosure relates to firearms configured to fire rimfire cartridges, but having one or more components also configured for use with other components configured to fire centerfire cartridges. The present disclosure also relates to methods of manufacturing and assembling such firearms, and to methods of using firearms in which a firearm configured to fire centerfire cartridges is adapted for firing rimfire cartridges.

BACKGROUND

A shoulder firearm is a firearm that is configured to abut against the shoulder of a person firing the firearm. A shoulder firearm includes a central receiver assembly, a stock attached to the receiver assembly, and a barrel extending distally from the receiver assembly. The stock is configured to abut against the shoulder of a person firing the firearm, and is used to assist in supporting and steadying the firearm while aiming and firing the firearm. Shoulder firearms include, for example, rifles, shotguns, muzzleloaders, etc.

A rifle is a shoulder firearm that includes one or more spiral grooves formed in the inner walls of the barrel, which are used to cause a bullet traveling down the barrel to spin, which results in improved stability and trajectory of the bullet subsequent to exiting the muzzle of the barrel.

Rifles are typically configured to fire a preloaded ammunition referred to in the art as a “cartridge.” The cartridge includes a generally cylindrical case having an open forward end and a closed rearward end, primer disposed within the case at the closed rearward end, gun powder disposed within the case, and a bullet at the open forward end of the case. The open forward end of the case is typically sealed (e.g., crimped) around the bullet to enclose the gun powder within the case.

Rifles typically include a firing chamber formed in a proximal end of the barrel, which is often referred to in the art as the “breech.” The receiver assembly includes a relatively large number of components that are assembled together and form the mechanisms of the firearm. For example, the receiver assembly includes an action mechanism that moves cartridges into the firing chamber, typically from a magazine, tube, or other component configured to hold one or more unfired cartridges therein. The action mechanism also extracts cartridges (or cases of fired cartridges) out from the firing chamber and ejects the cartridges from the receiver assembly. The action mechanism typically includes a bolt that is disposed proximal to the firing chamber. The bolt slides back and forth generally parallel to the longitudinal axis of the barrel between an open position and closed position. In the closed position, the distal end of the bolt defines the proximal surface of the firing chamber.

As the bolt moves from the open position to the closed position, the bolt engages a cartridge held within the magazine or tube and forces the cartridge into the firing chamber. One or more features are typically carried by the bolt that engage complementary features on the case of the cartridge such that, as the bolt moves from the closed position to the open position, the bolt pulls the cartridge or case out from the firing chamber and manipulates the cartridge in a manner causing the cartridge to be ejected from the receiver assembly of the firearm.

Rifle cartridges are manufactured in two common configurations. One of these configurations is the “rimfire” configuration, and the other configuration is the “centerfire” configuration.

FIG. 16 illustrates an example of a rimfire cartridge 170. The rimfire cartridge 170 of FIG. 16 is a .22 long rifle rimfire cartridge. The cartridge 170 includes a case 172 and a bullet 174. The case has a closed rearward end 176 and an open end 178. The bullet 174 is attached to the case 172 at the open end 178 of the case 172. In a rimfire cartridge 170, the closed rearward end 176 of the case 172 generally includes a radially extending rim 180. During manufacture of the cartridge 170, a primer compound is disposed in the case 172, and a centrifuge is generally used to dispose the primer compound within the annular-shaped protruding rim 180 of the cartridge 170. The firing pin of the firearm is configured to strike the rim 180 of the cartridge 170, which contains the primer therein. The primer combusts and ignites combustion of the gun powder. The expanding gases generated by ignition of the gun powder force the bullet 174 out from the case 172 of the cartridge 170 and through the barrel. Thus, in a rimfire firearm, the firing pin is not aligned with the longitudinal axis of the barrel or the center of a cartridge 170 contained in the firing chamber.

FIG. 15 illustrates an example of a centerfire cartridge 150. The centerfire cartridge 150 of FIG. 15 is a .308 WINCHESTER centerfire cartridge. The cartridge 150 includes a case 152 and a bullet 154. The case 152 has a closed rearward end 156 and an open end 158. The bullet 154 is attached to the case 152 at the open end 158 of the case 152. In a centerfire cartridge 150, the primer is located at the center of the closed rearward end 156 of the case 152. Generally, the primer is a separate and replaceable component of a centerfire cartridge 150. The firing pin of the firearm is configured to strike the exterior surface of the primer component, which causes a primer compound carried by the primer within the case 152 to combust. The combustion of the primer compound ignites combustion of the gun powder, and the expanding gases generated by ignition of the gun powder force the bullet 154 out from the case 152 of the cartridge 150 and through the barrel. Thus, in a centerfire firearm, the firing pin is aligned with the longitudinal axis of the barrel and the center of a cartridge 150 contained in the firing chamber.

Generally, rimfire cartridges are significantly less expensive than centerfire cartridges. This is due, at least in part, to the methods used to manufacture the cartridges. Rimfire cartridges, however, are generally not capable of handling internal pressures as high as those that may be handled by centerfire cartridges. Centerfire cartridges are generally capable of exhibiting longer range, higher power, improved accuracy, and higher kinetic energy delivered to a target by the bullet, since they are capable of being used in a reliable manner with higher quantities of gun powder, and the resulting higher pressures generated by combustion of the gun powder, compared to rimfire cartridges. As a result, rimfire cartridges are generally limited to relatively small caliber cartridges, while larger caliber cartridges generally comprise centerfire cartridges.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a perspective view of a left side of a shoulder firearm of the present disclosure.

FIG. 2 is a perspective view of a right side of the shoulder firearm of FIG. 1.

FIG. 3 is a perspective view of a left side of a receiver assembly of the firearm of FIGS. 1 and 2 with the barrel and stock removed, but with a magazine coupled to the receiver assembly, wherein the receiver assembly includes a lower portion and an upper portion.

FIG. 4 is a perspective view of a right side of the receiver assembly of FIG. 3.

FIG. 5 is a plan view of the left side of the receiver assembly of FIGS. 3 and 4.

FIG. 6 is a plan view of the right side of the receiver assembly of FIGS. 3 through 5.

FIG. 7 is a plan view of a left side of the lower portion of the receiver assembly with the upper portion and the magazine removed.

FIG. 8 is a plan view of a right side of the lower portion of the receiver assembly with the upper portion and the magazine removed.

FIG. 9 is a plan view of a bottom side of the lower portion with the upper portion and the magazine removed.

FIG. 10 is a plan view of a right side of the upper portion of the receiver assembly with the lower portion and the magazine removed.

FIG. 11 is a plan view of a left side of the upper portion with the lower portion and the magazine removed.

FIG. 12 is a plan view of a bottom side of the upper portion with the lower portion and the magazine removed.

FIG. 13 is a plan view of a left side of the magazine of the firearm of FIGS. 1 and 2 separate from the other components of the firearm.

FIG. 14 is a perspective view of the magazine shown in FIG. 13.

FIG. 15 is a side plan view of a rimfire rifle cartridge.

FIG. 16 is a side plan view of a centerfire rifle cartridge.

DETAILED DESCRIPTION

The illustrations presented herein are not meant to be actual views of any particular firearm, or component thereof, but are merely idealized representations that are used to describe embodiments of the disclosure.

As used herein, the term “proximal,” when used in relation to a firearm or a component of a firearm, means proximate or nearer to the body of a person firing the firearm. As used herein, the term “distal,” when used in relation to a firearm or a component of a firearm, means remote or farther from the body of a person firing the firearm.

The present invention relates to the adaptation of a firearm configured for use with centerfire cartridges, such as the cartridge 150 of FIG. 15, which cartridges are generally relatively large and expensive, such that the firearm may be used with relatively smaller and less expensive rimfire cartridges, such as the cartridge 170 of FIG. 16 for example. The adaptation may be temporary in nature, such that the firearm may be again reconfigured for use with centerfire cartridges.

FIGS. 1 and 2 illustrate an example of a shoulder firearm 100 of the present disclosure. The shoulder firearm 100 is a rifle. The firearm 100 includes a stock 102, a receiver assembly 104, and a barrel 110. The firearm 100 also includes a magazine 112 that is configured to hold a plurality of unfired cartridges therein. In some embodiments, the magazine 112 may be configured to be repeatedly coupled to and decoupled from the receiver assembly 104.

The receiver assembly 104 is attached to the stock 102, and includes a lower portion 106 and an upper portion 108 that are assembled together to form the receiver assembly 104. The receiver assembly 104 is described in further detail below with reference to FIGS. 3 through 6. The lower portion 106 is described below with reference to FIGS. 7 through 9, and the upper portion 108 is described below with reference to FIGS. 10 through 12.

As described in further detail below, each of the barrel 110, the upper portion 108, and the magazine 112 may be sized and configured for use with rimfire cartridges, such as the cartridge 170 of FIG. 16, while the stock 102 and lower portion 106 may have been originally configured for use with centerfire cartridges, such as the cartridge 150 of FIG. 15. The upper portion 108 and the magazine 112, which are configured for use with rimfire cartridges, thus, may be sized and configured to couple and operate with the lower portion and stock, which were sized and configured for use with centerfire cartridges.

As shown in FIGS. 1 and 2, the firearm 100 may comprise a manually operated bolt action rifle in some embodiments. In other embodiments, however, the firearm 100 may comprise a semiautomatic or a fully automatic firearm.

The stock 102 may comprise wood, a synthetic material, or a chassis system (e.g., a metal or synthetic modular stock-like assembly). The stock 102 may comprise a portion 103A configured to extend proximally from the receiver assembly 104 and abut against a shoulder of a person using the firearm 100. In some embodiments, the stock 102 also may comprise a second portion 103B configured to extend distally from the receiver assembly 104 beneath at least a portion of the barrel 110. The second portion 103B may comprise a handgrip sized and configured to be gripped by a non-trigger hand of a person using the firearm. In such embodiments, the first and second portions 103A, 103B of the stock 102 may be regions of a single unitary body. In other embodiments, the first and second portions 103A, 103B may comprise separate bodies that may be attached directly or indirectly to one another. In yet further embodiments, the stock 102 may include only the first portion 103A that is configured to abut against a shoulder of a person using the firearm, or the stock 102 may include only the second portion 103B that is configured to be gripped by a non-trigger hand of a person using the firearm 100.

FIGS. 3 through 6 illustrate the receiver assembly 104, as well as a magazine 112 coupled with the receiver assembly 104. As previously mentioned, the receiver assembly 104 includes an upper portion 108 and a lower portion 106. The receiver assembly 104 includes various stationary and movable components that, when assembled together, form the mechanisms of the firearm. The mechanisms include an action mechanism and a trigger mechanism. The action mechanism is the mechanism that moves unfired cartridges from the magazine 112 into the firing chamber of the firearm 100, and that moves cartridges (or cases of fired cartridges) out from the firing chamber and ejects the cartridges out from the receiver assembly 104. The trigger mechanism is the mechanism that, upon actuation by a person using the firearm, causes a firing pin to move in a distal direction and strike a cartridge in the firing chamber and fire the ammunition. The firing pin is part of the upper portion 108. The firing pin of the firearm 100 is configured to strike a rim of a rimfire cartridge, such as the rim 180 of the rimfire cartridge 170 of FIG. 16, in the firing chamber of the firearm 100 upon actuation of a trigger.

The action mechanism includes a bolt 114, which is part of the upper portion 108. The bolt 114 is disposed proximal to the firing chamber, and is movable between an open position and a closed position. The bolt 114 is shown in the closed position in the figures. In some embodiments, the firing pin may be carried on or in the bolt 114.

FIGS. 7 through 9 illustrate the lower portion 106 separate from the other components of the firearm 100. As shown in FIGS. 7 through 9, the lower portion 106 includes a trigger guard 116 and a magazine housing 120. In some embodiments, the trigger guard 116 and the magazine housing 120 may be portions of a single unitary body. In other embodiments, the trigger guard 116 and the magazine housing 120 may be separate components that may be assembled together.

The trigger guard 116 is configured to extend around a trigger, which is not shown in the figures, in such a manner as to prevent unintentional movement of the trigger. The trigger, and various other components of a trigger assembly, may be operatively coupled with the trigger housing. The trigger assembly provides a linkage between the trigger and the firing pin, such that pull of the trigger causes movement of the firing pin. The trigger assembly also may include one or more components of a safety mechanism used to prevent accidental pull of the trigger and/or movement of the firing pin.

The magazine housing 120 is configured to receive the magazine 112 (FIGS. 1 through 6) therein. Thus, as shown in FIG. 9, the magazine housing 120 has a shape and configuration defining a magazine receptacle 122 therein. As shown in FIG. 9, the magazine receptacle 122 may have a longitudinal length L₁₂₂ and a transverse width W₁₂₂. The longitudinal length L₁₂₂ is greater than the transverse width W₁₂₂. As previously mentioned, the lower portion 106, and, hence, the magazine housing 120, may have been originally designed and manufactured for use with relatively larger (e.g., longer) centerfire cartridges, such as the cartridge 150 of FIG. 15 for example. As a result, the longitudinal length L₁₂₂ of the magazine receptacle 122 in the magazine housing 120 may be longer than the typical longitudinal length of such magazine receptacles in magazine housings of firearms configured for use with relatively smaller (e.g., shorter) rimfire cartridges, such as the rimfire cartridge 170 of FIG. 16. As non-limiting examples, the longitudinal length L₁₂₂ of the magazine receptacle 122 in the magazine housing 120 may be greater than about 1.5 inches, greater than about 2.0 inches, greater than about 2.5 inches, or even greater than about 3.0 inches. For example, if the lower portion 106, and, hence, the magazine housing 120, were originally designed and manufactured for use with .308 WINCHESTER centerfire cartridges, the longitudinal length L₁₂₂ of the magazine receptacle 122 in the magazine housing 120 may be about 3.16 inches.

FIGS. 10 through 12 illustrate the upper portion 108 of the receiver assembly 104 of the firearm 100 separate from the other components of the firearm 100. As shown in FIGS. 10 through 12, the upper portion 108 may include an outer bolt housing 126, and a bolt 114 configured to slide back and forth in the longitudinal direction within the outer bolt housing 126. A manual lever 128 may be attached to the bolt 114 to allow a person using the firearm 100 to manually move the bolt 114 back and forth between the open rearward position and the closed forward position. Thus, the firearm 100 may be a manual bolt action firearm 100, as opposed to a semi-automatic or fully automatic firearm. The bolt and lever 128 are shown in the closed forward position in the figures. As shown in FIGS. 10 and 11, the outer bolt housing 126 may include an ejection opening 130 through which cartridges or cases of fired cartridges are ejected from the firearm 100 as they are pulled backward in the proximal direction out from the firing chamber by the bolt 114. As the upper portion 108 is configured for use with relatively smaller (e.g., shorter) rimfire cartridges (e.g., the rimfire cartridge 170 of FIG. 16), the ejection opening 130 may have a longitudinal length L₁₃₀ that is less than about 3.0 inches, less than about 2.5 inches, less than about 2.0 inches, or even less than about 1.5 inches. For example, if the upper portion 108, and, hence, the bolt 114 and outer bolt housing 126, are configured for use with .22 Long Rifle rimfire cartridges 170, the longitudinal length L₁₃₀ of the ejection opening 130 in the outer bolt housing 126 may be about 2.12 inches.

Similarly, the stroke length of the bolt 114, which is the distance the bolt 114 travels between the open position and the closed position, may be less than about 3.0 inches, less than about 2.5 inches, less than about 2.0 inches, or even less than about 1.75 inches. For example, if the upper portion 108, and, hence, the bolt 114 and outer bolt housing 126, are configured for use with .22 Long Rifle rimfire cartridges 170, the stroke of the bolt 114 may be about 1.585 inches.

As shown in FIG. 12, the outer bolt housing 126 may include an insertion opening 132 through which unfired cartridges are received from the magazine 112 as the cartridges are being moved into the firing chamber by forward, distal movement of the bolt 114. Again, as the upper portion 108 is configured for use with relatively smaller (e.g., shorter) rimfire cartridges (e.g., the rimfire cartridge 170 of FIG. 16), the insertion opening 132 may have a longitudinal length L₁₃₂ that is less than about 3.0 inches, less than about 2.5 inches, less than about 2.0 inches, or even less than about 1.5 inches. For example, if the upper portion 108, and, hence, the bolt 114 and outer bolt housing 126, are configured for use with .22 Long Rifle rimfire cartridges 170, the longitudinal length L₁₃₂ of the insertion opening 132 in the outer bolt housing 126 may be about 1.26 inches.

FIGS. 13 and 14 illustrate the magazine 112. The magazine 112 of the firearm 100 of the present disclosure has external dimensions and an external configuration that is configured to couple with the magazine housing 120 and the magazine receptacle 122 (FIG. 9) of the lower assemble 106, which are configured for use with relatively larger centerfire cartridges (e.g., the centerfire cartridge 150 of FIG. 15), but has internal dimensions and an internal configuration that are configured to receive and store relatively smaller rimfire cartridges (e.g., the rimfire cartridge 170) therein. The magazine 112 is also configured to couple with the upper portion 108, when the magazine 112 is coupled with the receiver assembly 104, in such a manner as to allow a rimfire cartridge 170 contained in the magazine 112 to be fed into the upper portion 108 through the insertion opening 132 in the lower surface of the outer bolt housing 126 (FIG. 12). Thus, the magazine 112 may have an external longitudinal length L₁₁₂ and a transverse width W₁₁₂. The external longitudinal length L₁₁₂ and a transverse width W₁₁₂ may be generally similar too, but slightly smaller than, the longitudinal length L₁₂₂ and the transverse width W₁₂₂, respectively, of the magazine receptacle 122 to allow the magazine 112 to be received tightly in, and secured within, the magazine receptacle 122 in the magazine housing 120. The longitudinal length L₁₁₂ of the magazine 112 may be longer than the typical longitudinal length of such magazines of firearms configured for use with relatively smaller (e.g., shorter) rimfire cartridges 170. As non-limiting examples, the longitudinal length L₁₁₂ of the magazine 112 may be greater than about 1.5 inches, greater than about 2.0 inches, greater than about 2.5 inches, or even greater than about 3.0 inches. For example, if the lower portion 106 was originally designed and manufactured for use with .308 WINCHESTER centerfire cartridges 150, the longitudinal length L₁₁₂ of the magazine 112 may be about 3.06 inches, and the transverse width W₁₁₂ of the magazine 112 may be about 0.974 inches.

The magazine 112, however, is configured to receive relatively smaller (e.g., shorter) rimfire cartridges 170 therein. Thus, a storage rack 134 may be provided within the magazine 112 that is configured to receive and store such smaller rimfire cartridges 170 therein in a vertical stack. The storage rack 134 may protrude from the top of the outer housing of the magazine 112, as shown in FIGS. 13 and 14, so as to project into or proximate the insertion opening 132 in the outer bolt housing 126 of the upper portion 108 when the magazine 112 is coupled with the receiver assembly 104. The storage rack 134 may have a longitudinal length L₁₃₄ that is relatively shorter than the longitudinal length L₁₁₂ of the magazine, as shown in FIG. 13. By way of example and not limitation, the longitudinal length L₁₃₄ of the storage rack 134 may be about 75% or less of the longitudinal length L₁₁₂ of the magazine 112, about 50% or less of the longitudinal length L₁₁₂ of the magazine 112, or even about 35% or less of the longitudinal length L₁₁₂ of the magazine 112. As a result, a significant interior volume of the magazine 112 is not occupied by cartridges 170 when the magazine is fully loaded with cartridges 170, in contrast to previously known magazines. For example, the rimfire cartridges 170 may occupy about 60% or less of the internal volume of the magazine 112, about 50% or less of the internal volume of the magazine 112, or even about 40% or less of the internal volume of the magazine 112, when the magazine 112 is fully loaded with the rimfire cartridges 170. In this configuration, the magazine 112 may not be capable of receiving cartridges (e.g., centerfire cartridges 150) therein having a length greater than about 75% of the external longitudinal length L₁₁₂ of the magazine 112, greater than about 50% of the external longitudinal length L₁₁₂ of the magazine 112, greater than about 40% of the external longitudinal length L₁₁₂ of the magazine 112, or even greater than about 35% of the external longitudinal length L₁₁₂ of the magazine 112.

The “headspace” in a firing chamber of a firearm is defined as the distance from the distal, forward surface of the bolt 114 when the bolt is in the forward closed position, to the feature, such as a seat surface, in the firing chamber against which a portion of the case abuts as the cartridge is inserted into the firing chamber such that further forward movement of the cartridge in the firing chamber is precluded. In a rimfire cartridge, such as the rimfire cartridge 170 of FIG. 16, the headspace 182 is defined by the thickness of the annular protruding rim 180 of the case 172 of the cartridge 170. In a centerfire cartridge, such as the centerfire cartridge 150 of FIG. 15, the headspace 160 is defined by a surface forming a narrowed or “necked-down” region of the case 152 at or near the open proximal end 158 of the case 152. Thus, the headspace of centerfire cartridges is generally significantly longer than the headspace of rimfire cartridges. In accordance with embodiments of the present disclosure, the headspace in a firearm 100 of the present disclosure may be about 0.075″ or less, for example.

As will be appreciated from the above description, the firearm 100 of the present disclosure is distinguishable from previously known firearms by, for example, the difference in size between the exterior dimensions of the magazine 112 and the dimensions of each of the internal storage rack 124 within the magazine 112, the ejection opening 130 and the insertion opening 132 of the outer bolt housing 126, the stroke length of the bolt 114, the firing chamber, and the headspace within the firing chamber.

Additional embodiments of the present disclosure include methods of manufacturing a firearm 100 as described herein, as well as method of adapting a firearm 100 configured for use with centerfire cartridges for use with rimfire cartridges.

For example, a barrel 110, upper portion 108, and magazine 112 as described hereinabove may be fabricated or otherwise provided. A firearm may be selected that is configured for use with centerfire rifle cartridges. As a non-limiting example, a .308 WINCHESTER caliber firearm may be selected. The barrel and upper portion of the firearm may be removed, and the barrel 110 and upper portion 108 may be assembled with the stock 102 and lower portion 106 of the .308 WINCHESTER caliber firearm. The magazine 112 may have exterior dimensions and a configuration configured to couple with the magazine housing and the lower portion 106 of the .308 WINCHESTER caliber firearm, but the storage rack 134 may be configured to receive and store, for example, .22 long rifle rimfire cartridges therein. Similarly, the barrel 110 and the upper portion 108 may be configured for firing .22 long rifle rimfire cartridges therein. Upon assembly, a firearm 100 as described herein is formed, which includes a stock 102 and lower portion 106 of a .308 WINCHESTER caliber firearm, but that is configured to fire .22 long rifle rimfire cartridges.

Such .22 long rifle rimfire cartridges are significantly less expensive than .308 WINCHESTER centerfire cartridges. As a result, personnel, such as military or police personnel, may participate in training exercises using a .308 WINCHESTER caliber centerfire firearm while firing relatively inexpensive .22 long rifle rimfire cartridges therefrom. Upon completion of the training exercises, the firearm may be reconfigured for firing .308 WINCHESTER caliber centerfire cartridges therefrom by removing the barrel 110, upper portion 108, and magazine 112, and replacing them with the original barrel, upper portion, and magazine of the .308 WINCHESTER caliber centerfire firearm, which were configured for use with .308 WINCHESTER caliber centerfire cartridges.

Additional non-limiting example embodiments of the disclosure are set forth below.

Embodiment 1

A firearm, comprising: a stock; a receiver assembly attached to the stock, the receiver assembly including a lower portion and an upper portion; a barrel extending from the receiver assembly; a firing chamber located at the proximal end of the barrel; and a magazine configured for holding a plurality of unfired rimfire cartridges therein, the magazine configured to be repeatedly coupled to and decoupled from the receiver assembly; wherein the upper portion comprises an action mechanism configured to move an unfired rimfire cartridge from the magazine into the firing chamber, and to remove the rimfire cartridge from the firing chamber and to eject the rimfire cartridge from the receiver assembly, the action mechanism including a bolt disposed proximal to the firing chamber and movable between an open position and a closed position, the upper portion further comprising a firing pin configured to strike a rim of a rimfire cartridge in the firing chamber upon actuation of a trigger; wherein the lower portion comprises a trigger mechanism configured to cause movement of the firing pin upon actuation of a trigger of the trigger mechanism, the lower portion further comprising a housing defining a receptacle configured to receive the magazine therein; and wherein the lower portion of the receiver assembly is sized and configured for use with another upper portion and another magazine, the another upper portion and another magazine configured for use with centerfire cartridges.

Embodiment 2

The firearm of Embodiment 1, wherein the magazine has an external length, width, and height, and wherein the magazine is not capable of receiving cartridges therein having a length greater than about 75% of the external length of the magazine.

Embodiment 3

The firearm of Embodiment 2, wherein the magazine is not capable of receiving cartridges therein having a length greater than about 50% of the external length of the magazine.

Embodiment 4

The firearm of Embodiment 3, wherein the magazine is not capable of receiving cartridges therein having a length greater than about 40% of the external length of the magazine.

Embodiment 5

The firearm of Embodiment 4, wherein the magazine is not capable of receiving cartridges therein having a length greater than about 35% of the external length of the magazine.

Embodiment 6

The firearm of any one of Embodiments 1 through 5, wherein the firearm has a headspace of 0.075″ or less.

Embodiment 7

The firearm of any one of Embodiments 1 through 6, wherein the firing chamber is sized and configured to fire one of .17 HORNADY MACH 2 cartridges, .17 HORNADY MAGNUM RIMFIRE cartridges, 5 mm REMINGTON RIMFIRE MAGNUM cartridges, .22 long rifle rimfire cartridges, and .22 WINCHESTER MAGNUM RIMFIRE cartridges.

Embodiment 8

A method of manufacturing a firearm, comprising: providing a barrel configured for used with rimfire cartridges; forming an upper portion configured for use with rimfire cartridges, the upper portion comprising an action mechanism configured to move an unfired rimfire cartridge from a magazine into a firing chamber at least partially defined in a proximal end of the barrel, and to remove the rimfire cartridge from the firing chamber and to eject the rimfire cartridge from the receiver assembly, the action mechanism including a bolt disposed proximal to the firing chamber and movable between an open position and a closed position, the upper portion further comprising a firing pin configured to strike a rim of a rimfire cartridge in the firing chamber upon actuation of a trigger; attaching the upper portion and the barrel to a lower portion and a stock sized and configured for use with another upper portion and another barrel each configured for use with centerfire cartridges, the lower portion comprising at least a portion of a trigger mechanism configured to cause movement of the firing pin upon actuation of a trigger of the trigger mechanism, the lower portion further comprising a housing defining a receptacle configured to receive a magazine therein; and providing a magazine configured for holding a plurality of unfired rimfire cartridges therein, the magazine configured to be repeatedly coupled to and decoupled from the upper portion and lower portion.

Embodiment 9

The method of Embodiment 8, further comprising forming the magazine.

Embodiment 10

The method of Embodiment 9, wherein forming the magazine comprises forming the magazine to have an external length, width, and height, and configuring the magazine such that the magazine is not capable of receiving cartridges therein having a length greater than about 75% of the external length of the magazine.

Embodiment 11

The method of Embodiment 10, further comprising configuring the magazine such that the magazine is not capable of receiving cartridges therein having a length greater than about 50% of the external length of the magazine.

Embodiment 12

The method of Embodiment 11, further comprising configuring the magazine such that the magazine is not capable of receiving cartridges therein having a length greater than about 40% of the external length of the magazine.

Embodiment 13

The method of Embodiment 12, further comprising configuring the magazine such that the magazine is not capable of receiving cartridges therein having a length greater than about 35% of the external length of the magazine.

Embodiment 14

The method of any one of Embodiments 8 through 13, further comprising configuring the upper portion such that the firearm has a headspace of 0.075″ or less.

Embodiment 15

The method of any one of Embodiments 8 through 14, further comprising selecting the barrel and configuring each of the upper portion and magazine for use with one of .17 HORNADY MACH 2 cartridges, .17 HORNADY MAGNUM RIMFIRE cartridges, 5 mm REMINGTON RIMFIRE MAGNUM cartridges, .22 long rifle rimfire cartridges, and .22 WINCHESTER MAGNUM RIMFIRE cartridges.

Embodiment 16

The method of any one of Embodiments 8 through 15, further comprising selecting the stock and the lower portion to comprise a stock and a lower portion of a firearm configured to fire .308 WINCHESTER centerfire cartridges.

Embodiment 17

A method of using a firearm, comprising: selecting a firearm configured to fire centerfire cartridges; removing a first barrel and a first upper portion of a first receiver assembly from the firearm; providing a second barrel and a second upper portion configured for use with rimfire cartridges, the second upper portion comprising an action mechanism configured to move an unfired rimfire cartridge from a magazine into a firing chamber at least partially defined in a proximal end of the second barrel, and to remove the rimfire cartridge from the firing chamber and to eject the rimfire cartridge from the upper portion, the action mechanism including a bolt disposed proximal to the firing chamber and movable between an open position and a closed position, the second upper portion further comprising a firing pin configured to strike a rim of a rimfire cartridge in the firing chamber upon actuation of a trigger; attaching the second upper portion and the second barrel to a lower portion and a stock of the firearm, the lower portion comprising at least a portion of a trigger mechanism configured to cause movement of the firing pin upon actuation of a trigger of the trigger mechanism, the lower portion further comprising a housing defining a receptacle configured to receive a magazine therein; and providing a magazine configured for holding a plurality of unfired rimfire cartridges therein, the magazine configured to be repeatedly coupled to and decoupled from the second upper portion and the lower portion.

Embodiment 18

The method of Embodiment 17, further comprising selecting the magazine to have an external length and width, the magazine not being capable of receiving cartridges therein having a length greater than about 75% of the external length of the magazine.

Embodiment 19

The method of Embodiment 18, wherein the magazine is not capable of receiving cartridges therein having a length greater than about 50% of the external length of the magazine.

Embodiment 20

The method of Embodiment 19, wherein the magazine is not capable of receiving cartridges therein having a length greater than about 35% of the external length of the magazine.

Embodiment 21

The method of any one of Embodiments 17 through 20, further comprising selecting the second barrel, the second upper portion, and the magazine for use with one of .17 HORNADY MACH 2 cartridges, .17 HORNADY MAGNUM RIMFIRE cartridges, 5 mm REMINGTON RIMFIRE MAGNUM cartridges, .22 long rifle rimfire cartridges, and .22 WINCHESTER MAGNUM RIMFIRE cartridges.

Embodiment 22

The method of any one of Embodiments 17 through 21, wherein selecting the firearm comprises selecting a firearm configured for firing .308 WINCHESTER centerfire cartridges.

The example embodiments of the disclosure described above do not limit the scope of the invention, since these embodiments are merely examples of embodiments of the invention, which is defined by the scope of the appended claims and their legal equivalents. Any equivalent embodiments are intended to be within the scope of this invention. Indeed, various modifications of the disclosure, in addition to those shown and described herein, such as alternate useful combinations of the elements described, will become apparent to those skilled in the art from the description. Such modifications and embodiments are also intended to fall within the scope of the appended claims. 

What is claimed is:
 1. A firearm, comprising: a stock; a receiver assembly attached to the stock, the receiver assembly including a lower portion and an upper portion; a barrel extending from the receiver assembly; a firing chamber located at the proximal end of the barrel; and a magazine configured for holding a plurality of unfired rimfire cartridges therein, the magazine configured to be repeatedly coupled to and decoupled from the receiver assembly; wherein the upper portion comprises an action mechanism configured to move an unfired rimfire cartridge from the magazine into the firing chamber, and to remove the rimfire cartridge from the firing chamber and to eject the rimfire cartridge from the receiver assembly, the action mechanism including a bolt disposed proximal to the firing chamber and movable between an open position and a closed position, the upper portion further comprising a firing pin configured to strike a rim of a rimfire cartridge in the firing chamber upon actuation of a trigger; wherein the lower portion comprises a trigger mechanism configured to cause movement of the firing pin upon actuation of a trigger of the trigger mechanism, the lower portion further comprising a housing defining a receptacle configured to receive the magazine therein; and wherein the lower portion of the receiver assembly is sized and configured for use with another upper portion and another magazine, the another upper portion and another magazine configured for use with centerfire cartridges.
 2. The firearm of claim 1, wherein the magazine has an external length, width, and height, and wherein the magazine is not capable of receiving cartridges therein having a length greater than about 75% of the external length of the magazine.
 3. The firearm of claim 2, wherein the magazine is not capable of receiving cartridges therein having a length greater than about 50% of the external length of the magazine.
 4. The firearm of claim 3, wherein the magazine is not capable of receiving cartridges therein having a length greater than about 40% of the external length of the magazine.
 5. The firearm of claim 4, wherein the magazine is not capable of receiving cartridges therein having a length greater than about 35% of the external length of the magazine.
 6. The firearm of claim 1, wherein the firearm has a headspace of 0.075″ or less.
 7. The firearm of claim 1, wherein the firing chamber is sized and configured to fire one of .17 HORNADY MACH 2 cartridges, .17 HORNADY MAGNUM RIMFIRE cartridges, 5 mm REMINGTON RIMFIRE MAGNUM cartridges, .22 long rifle rimfire cartridges, and .22 WINCHESTER MAGNUM RIMFIRE cartridges.
 8. A method of manufacturing a firearm, comprising: providing a barrel configured for used with rimfire cartridges; forming an upper portion configured for use with rimfire cartridges, the upper portion comprising an action mechanism configured to move an unfired rimfire cartridge from a magazine into a firing chamber at least partially defined in a proximal end of the barrel, and to remove the rimfire cartridge from the firing chamber and to eject the rimfire cartridge from the receiver assembly, the action mechanism including a bolt disposed proximal to the firing chamber and movable between an open position and a closed position, the upper portion further comprising a firing pin configured to strike a rim of a rimfire cartridge in the firing chamber upon actuation of a trigger; attaching the upper portion and the barrel to a lower portion and a stock sized and configured for use with another upper portion and another barrel each configured for use with centerfire cartridges, the lower portion comprising at least a portion of a trigger mechanism configured to cause movement of the firing pin upon actuation of a trigger of the trigger mechanism, the lower portion further comprising a housing defining a receptacle configured to receive a magazine therein; and providing a magazine configured for holding a plurality of unfired rimfire cartridges therein, the magazine configured to be repeatedly coupled to and decoupled from the upper portion and lower portion.
 9. The method of claim 8, further comprising forming the magazine.
 10. The method of claim 9, wherein forming the magazine comprises forming the magazine to have an external length, width, and height, and configuring the magazine such that the magazine is not capable of receiving cartridges therein having a length greater than about 75% of the external length of the magazine.
 11. The method of claim 10, further comprising configuring the magazine such that the magazine is not capable of receiving cartridges therein having a length greater than about 50% of the external length of the magazine.
 12. The method of claim 11, further comprising configuring the magazine such that the magazine is not capable of receiving cartridges therein having a length greater than about 40% of the external length of the magazine.
 13. The method of claim 12, further comprising configuring the magazine such that the magazine is not capable of receiving cartridges therein having a length greater than about 35% of the external length of the magazine.
 14. The method of claim 8, further comprising configuring the upper portion such that the firearm has a headspace of 0.075″ or less.
 15. The method of claim 8, further comprising selecting the barrel and configuring each of the upper portion and magazine for use with one of .17 HORNADY MACH 2 cartridges, .17 HORNADY MAGNUM RIMFIRE cartridges, 5 mm REMINGTON RIMFIRE MAGNUM cartridges, .22 long rifle rimfire cartridges, and .22 WINCHESTER MAGNUM RIMFIRE cartridges.
 16. The method of claim 15, further comprising selecting the stock and the lower portion to comprise a stock and a lower portion of a firearm configured to fire .308 WINCHESTER centerfire cartridges.
 17. A method of using a firearm, comprising: selecting a firearm configured to fire centerfire cartridges; removing a first barrel and a first upper portion of a first receiver assembly from the firearm; providing a second barrel and a second upper portion configured for use with rimfire cartridges, the second upper portion comprising an action mechanism configured to move an unfired rimfire cartridge from a magazine into a firing chamber at least partially defined in a proximal end of the second barrel, and to remove the rimfire cartridge from the firing chamber and to eject the rimfire cartridge from the upper portion, the action mechanism including a bolt disposed proximal to the firing chamber and movable between an open position and a closed position, the second upper portion further comprising a firing pin configured to strike a rim of a rimfire cartridge in the firing chamber upon actuation of a trigger; attaching the second upper portion and the second barrel to a lower portion and a stock of the firearm, the lower portion comprising at least a portion of a trigger mechanism configured to cause movement of the firing pin upon actuation of a trigger of the trigger mechanism, the lower portion further comprising a housing defining a receptacle configured to receive a magazine therein; and providing a magazine configured for holding a plurality of unfired rimfire cartridges therein, the magazine configured to be repeatedly coupled to and decoupled from the second upper portion and the lower portion.
 18. The method of claim 17, further comprising selecting the magazine to have an external length and width, the magazine not being capable of receiving cartridges therein having a length greater than about 75% of the external length of the magazine.
 19. The method of claim 18, wherein the magazine is not capable of receiving cartridges therein having a length greater than about 50% of the external length of the magazine.
 20. The method of claim 19, wherein the magazine is not capable of receiving cartridges therein having a length greater than about 35% of the external length of the magazine.
 21. The method of claim 17, further comprising selecting the second barrel, the second upper portion, and the magazine for use with one of .17 HORNADY MACH 2 cartridges, .17 HORNADY MAGNUM RIMFIRE cartridges, 5 mm REMINGTON RIMFIRE MAGNUM cartridges, .22 long rifle rimfire cartridges, and .22 WINCHESTER MAGNUM RIMFIRE cartridges.
 22. The method of claim 21, wherein selecting the firearm comprises selecting a firearm configured for firing .308 WINCHESTER centerfire cartridges. 